The present invention generally relates to centrifuges, and more specifically, but not exclusively, concerns a centrifuge system that is able remove soot and other fine particles as well as harmful organic compounds from a fluid.
Diesel engines are designed with relatively sophisticated air and fuel filters (cleaners) in an effort to keep dirt and debris out of the engine. Even with these air and fuel cleaners, dirt and debris, including engine-generated wear debris, will find a way into the lubricating oil of the engine. The result is wear on critical engine components and if this condition is left unsolved or not remedied, engine failure. For this reason, many engines are designed with full flow oil filters that continually clean the oil as it circulates between the lubricant sump and engine parts.
There are a number of design constraints and considerations for such full flow filters, and typically these constraints mean that such filters can only remove those dirt particles that are in the range of 10 microns or larger. While removal of particles of this size may prevent a catastrophic failure, harmful wear will still be caused by smaller particles of dirt that get into and remain in the oil. In order to try and address the concern over small particles, designers have gone to bypass filtering systems which filter a predetermined percentage of the total oil flow. The combination of a full flow filter in conjunction with a bypass filter reduces engine wear to an acceptable level, but not to the desired level. Since bypass filters may be able to trap particles less then approximately 10 microns, the combination of a full flow filter and bypass filter offers a substantial improvement over the use of only a full flow filter.
Centrifuges, both self-driven and externally driven types, are routinely used for bypass filtering because of their ability to remove small particles from fluids like oil. On the other hand, it was discovered that centrifuges are not able to remove “sticky” or neutral density contaminant, like fuel-oil oligomer compounds (e.g., sludge/varnish compounds), because the density of these types of contaminants is nearly equal to that of oil. These sticky contaminants are usually formed when oil and fuel are mixed together in high temperature environments, such as in engines. If not removed, the sticky contaminant can harm engine performance by coating surfaces throughout the engine and causing premature plugging of the full-flow filters. Further, the acidic nature of some of these organic compounds results in premature corrosion of engine components. For instance, the main bearings in engines are typically lead coated, and the lead on the bearings is highly susceptible to corrosion when exposed to acids. In some applications, depending on engine type, operating condition, fuel type and the like, depth-medium bypass filters are able remove these neutral density contaminants, but depth-medium bypass filter are typically unable to remove fine particulates.
Thus, there is a need for improvement in this area of technology.